I agree with your point but there are some people who would blame anyone and everyone when they find out they've been working for 2 weeks under a Campaign only to find their help coins worth 0.002BTC. The next thing they do is look for the OP of the Campaign thread. They don't understand the difference between a Campaign Manager and the Owner of the Campaign. They leave a negative trust under the Manager's name.
I've yet to come across a case where I could not find a solution to get the users paid. (Knocking on wood here) Ideally, I never will have to.
Suppose I don't have enough trust as you. My main account is Sr. Member. What is the minimum amount I should hold from the campaign manager besides the Escrow while running the campaign?
It depends.
Holding coins for more rounds means you have less troubles reminding to get your escrow restocked (or maybe even forgetting about it), for example, I'm holding funds sufficient for at least 6 rounds (=weeks) at BitBlender now.
On the other hand, it also means the runner has to trust you with more funds, and you have to take good care of them. I got other escrows I have restocked every other week.
As a bare minimum, I'd say you should hold funds sufficient for 2 weeks (+transaction fees/your fees), in some cases, that however can be ignored (for example if the campaign is scheduled to end after one).
Also, when does the Escrow pay the users?
Depends if the escrow setup is active or passive. An active escrow should pay users asap after the payment schedule is available.
A passive escrow should only get involved in the worst case.
Can I ask him to pay a fraction of his amount to the users if the Owner is late in his payments? I am saying this because earlier I ran a campaign and a delayed payment from the owner had me in trouble
That's a case to case situation you have to figure out for yourself, best with the help of the escrow.
There's no definitive answer as to at what point an escrow (if passive) should get involved.
In the end, the decision comes down to the escrow (and the manager).